The military alliance between the United Kingdom and Poland was formalised by the Anglo-Polish Agreement in 1939 and subsequent addenda of 1940 and 1944,[1] for mutual assistance in case of military invasion from Germany, as specified in a secret protocol.[2][3][4]

... in the event of any action which clearly threatened Polish independence, and which the Polish Government accordingly considered it vital to resist with their national forces, His Majesty's Government would feel themselves bound at once to lend the Polish Government all support in their power. They have given the Polish Government an assurance to this effect.

I may add that the French Government have authorised me to make it plain that they stand in the same position in this matter as do His Majesty's Government.[6]

On April 6, during a visit to London by the Polish foreign minister, it was agreed to formalise the guarantee as an Anglo-Polish military alliance, pending negotiations.[7][8]

Polish-British common defence pact

On August 25, two days after the Nazi-Soviet Pact, the Agreement of Mutual Assistance between the United Kingdom and Poland was signed. The agreement contained promises of mutual military assistance between the nations in the event either was attacked by some "European country". The United Kingdom, sensing a trend of German expansionism, sought to discourage German aggression by this show of solidarity. In a secret protocol of the pact, the United Kingdom offered assistance in the case of an attack on Poland specifically by Germany,[3] while in the case of attack by other countries the parties were required to "consult together on measures to be taken in common".[10] Both the United Kingdom and Poland were bound not to enter agreements with any other third countries which were a threat to the other.[11] Because of the pact's signing, Hitler postponed his planned invasion of Poland from August 26 until September 1.[12]

Franco-British mission to Moscow, August—September 1939

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Analysis

At the time Adolf Hitler was demanding the cession of the port of Danzig, an extraterritorial highway (the Reichsautobahn Berlin-Königsberg) across the Polish Corridor, and special privileges for the German minority within Poland. By the terms of the military alliance, each party (i.e. Poland and Britain) was free to decide whether to oppose with force any territorial encroachment, as the pact did not include any statement of either party's commitment to the defence of the other party's territorial integrity.[16] The Pact did contain provisions regarding "indirect threats" and attempts to undermine either party's independence by means of "economic penetration", a clear reference to the peculiar status of Danzig. Fearing all-out German invasion no matter what, Poland rejected the German demands.

On September 17 the Soviet Union invaded Poland through the eastern Polish border. This was in keeping with the Molotov-Ribbentrop Pact's secret protocol specifying the division of Poland. According to the Polish-British Common Defence Pact, the United Kingdom should give Poland “all the support and assistance in its power” if Poland was "engaged in hostilities with a European Power in consequence of aggression by the latter". The Polish ambassador in London, Raczyński, contacted the British Foreign Office pointing out that clause 1(b) of the agreement which concerned an "aggression by a European power" on Poland, should apply to the Soviet invasion. The Foreign SecretaryLord Halifax responded that the obligation of British Government towards Poland arising out of the Anglo-Polish Agreement, was restricted to Germany, according to the first clause of the secret protocol.[3]

Criticism

Polish historian Paweł Wieczorkiewicz wrote: "Polish leaders were not aware of the fact that England and France were not ready for war. They needed time to catch up with the Third Reich, and were determined to gain the time at any price". Publicist Stanisław Mackiewicz stated in the late 1940s: "To accept London's guarantees was one of the most tragic dates in the history of Poland. It was a mental aberration and madness". On the same day when Britain pledged her support of Poland, Lord Halifax stated: "We do not think this guarantee will be binding". Other British diplomat, Alexander Cadogan wrote in his diary: "Naturally, our guarantee does not give any help to Poland. It can be said that it was cruel to Poland, even cynical".

Polish - British military negotiations, carried out in London, ended up in fiasco. After lengthy talks, the British reluctantly pledged to bomb German military and installations if the Germans carried out attacks of this kind in Poland. Polish military leaders failed to obtain any more promises. At the same time, the Polish side negotiatied a military loan. Polish ambassador to Britain, Edward Raczyński, called these negotiations "a never-ending nightmare". Józef Beck in his memoirs wrote: "The negotiations, carried out in London by Colonel Adam Koc, immediately turned into theoretical discussion about our financial system. It was clear that Sir John Simon and Frederick Leith-Ross did not realize the gravity of the situation. They negotiated in purely financial terms, without consideration for the rules of the wartime alliance. As a result, the English offer gave us no grounds for quick reinforcement of our army."

On August 2, 1939, Great Britain finally agreed to grant Poland a military loan of £9 million, which was less than Turkey received at the same time. Poland had asked for a loan of £60 million.

^Hugh Ragsdale, The Soviets, the Munich Crisis, and the Coming of World War II; Cambridge University Press, 2004; ISBN1139450255, 9781139450256

^"On 31 March 1939 the British government guaranteed the independence (though not the territorial integrity) of Poland, in which they were joined by France."
Paul M. Hayes, 'Themes in Modern European History, 1890-1945', Routledge (1992), ISBN0-415-07905-5